Detective Strawberry is a member of the International Police force and is their ace detective. He has been after the Radioactive Uber Clan for years, after Popeye killed his daughter and blamed her death on demons. He has amassed boatloads of evidence of the RUC's crimes to use against them, and has arrested them several times. His higher-ups, however, let the RUC go, which caused him to cut ties with the police force to take matters into his own hands.
He does not appreciate the RUC making up a new, completely inaccurate backstory for him. It's extremely disrespectful.